Take-up sprocket for motion-picture machines



vJuly 8, i924;

11,500,450 5. swozoz TAKE-UP SPROCKET FOR MOTION PICTURE MACHINES Filed ABE. 26. 1921 inventor:

Patented .1111 8, 1924.

seaase Ff" i Q E BnoNIsLAw ewoznz, or wnnsaw, POLAND.

v 'lAKIEl-TJ'IB SPROCKET FOR MOTION-PICTURE MACHINES.

Application filed August 26. 1921. Serial N0."495,702.

To all whom it may concern:

Be it-known that I, BRONISLAW Gwoznz, a citizen of the Polish'Republic, residing at Warsaw, Poland, have invented certain new and useful Improvements in Take -Up Sprockets for Motion-Picture Machines (for which I have filed application in Germany August 2, 1920, patent not yet granted), of which the following is a specification.

My invention relates to kinematbgraphs and more especially to driving rollers for motion picture films. It is well known that the celluloid film strips employed in kinematographic apparatus are driven by toothed rollers, the teeth of which engage perforations along the edges of the film strip. It is also known that this manner of driving the picture strips wears the strip out very quickly, especially as in consequence of the extremely frequent change of pictures the strip is continuously stopped and started again.

It is a matter of experience that the portions of the strip between the perforations suffer most and are first destroyed by the teeth of the driving rollers, so that a film which is otherwise quite intact becomes prematurely useless.

It has now been ascertained that this serious drawback is partly caused by the fact that the perforations in the strips show certain, although small irregularities and that above all the relation of the film to the driving device is during motion subject to certain irregularities, be it that the film is not properly introduced into the apparatus, be it that in the film itself tensions are set up during manufacture which cause the film to take a somewhat oblique course when passing over the rollers. It will be obvious that if rigidly connected toothed rims on the conveying roller act upon films having such irregularities fine cracks will soon form in the film, especially around the edges of the perforations, which cause a tearing of the strip, especially from perforation to perforation. As irregularities in the film strip cannot be avoided, it is an object of my invention to so construct the driving rollers and accessories that they can adapt themselves to these irregularities. This can be effected by making the toothed rims or discs of the driving rollers to a certain. extent independent of one another, although they still cooperate in driving the strip. According to my invention, this is effected by adapting thetoothed rims 0r discs to rotate relatively to one an- 7 other, by connecting them through a differ ential gearing or the like. They are then capable of rotating relatively to one another and will yet turn round with the roller. A full description of the invention will be found in the following specification.

I am aware that it is known to drive filmstrips by means of two separate toothed discs which are permanently or only temporarily directly coupled by an external gearing or a pawl.

In the drawings afiixed to this specification and forming part thereof, my invention is illustrated by way of example. In the drawings Fig. 1 is a sectional elevation,

Fig. 2 is an end elevation,

Fig. 3 a section along line 0d and Fig. 4: a section along line ab in Fig. 1.

Referring to Fig. 1, l is the shaft of the driving roller, and 2 and 3 the two toothed discs which with their teeth engage the row of perforations along each edge of the film strip and thus cause the film to be carried along.

Upon the shaft 1 there is fixed a sleeve 14:, which in the middle between the discs 2 and 3 is provided with an annular collar 15. The hubs 8, 9 of the toothed discs are like wise provided with annular collars. These parts are connected by arms 16. which extend in the direction of the axis of the roller and are provided at their ends with rounded heads and in the middle with a rounded collar, as will be clearly seen particularly in Fig. 1. The middle portion rests loosely in the recesses 15 of the rings 15, while the rounded heads loosely engage appropriate recesses in the collars of the hubs 8 and 9 of the toothed discs 2 and 3. The rounded portions of the arms 16 permit a certain twist of the toothed discs 2 and 3 relatively to one another which amply sufiices to compensate the irregularities in the film or in its guidance, as stated in the introduction to this specification. Here also the shaft 1 is provided with a disc 12 in the dished portion of which (curved to approximately a semi-circle) helical springs 13 are located (Fig. 3), which abut at one end against a radial projection 17 of the disc 12 and at the other end against a projection 18 of the toothed disc 2 and which operate as before described.

As a matter of course, the number of arms s n t c nfin t e the num shown n th drawings, but may vary within w ide limits. nation, a shaft, a pair of toothed discsloosej It will also be obvious that other modificaand a collar fixed on said shaft intermediate tions in the construction or arrangement of said discs, and flat arms extending through parts may be made without departing from slots in said collarand engaging said discs 15 i the spirit of the invention, the principle of with their free ends, the contact surfaces of which has been set out in the introduction said arms with saidcollar and discs being to the specification and some of the embodirounded. ments of which have been illustrated by way In testimony whereof I aflix my signature. of example only. I I V 1 10 I claim- BRONISLAW GWOZDZ.

In a device of the kind described in combi- Y V 

